quarkusio/quarkus · error · RuntimeException

This method is not supported using this builder. Use #routeF

Error message

This method is not supported using this builder. Use #routeFunction(String, Consumer<Route>)

What it means

NonApplicationRootPathBuildItem.Builder intentionally rejects the generic routeFunction(Function<Router,Route>) overload because the framework needs an explicit path string to compute the final non-application route. The builder throws unconditionally in this overload to steer callers toward the path-aware routeFunction(String, Consumer<Route>) variant. This is a compile-time-avoidable but runtime-enforced API contract within the Quarkus build-time framework.

Source

Thrown at extensions/vertx-http/deployment/src/main/java/io/quarkus/vertx/http/deployment/NonApplicationRootPathBuildItem.java:282

    }

    /**
     * Per non-application endpoint instance.
     */
    public static class Builder extends RouteBuildItem.Builder {
        private final NonApplicationRootPathBuildItem buildItem;
        private RouteBuildItem.RouteType routeType = RouteBuildItem.RouteType.FRAMEWORK_ROUTE;
        private RouteBuildItem.RouteType routerType = RouteBuildItem.RouteType.FRAMEWORK_ROUTE;
        private String name;
        private String path;

        Builder(NonApplicationRootPathBuildItem buildItem) {
            this.buildItem = buildItem;
        }

        @Override
        public Builder routeFunction(Function<Router, Route> routeFunction) {
            throw new RuntimeException(
                    "This method is not supported using this builder. Use #routeFunction(String, Consumer<Route>)");
        }

        public Builder routeFunction(String route, Consumer<Route> routeFunction) {
            return orderedRoute(route, null, routeFunction);
        }

        @Override
        public Builder route(String route) {
            routeFunction(route, null);
            return this;
        }

        @Override
        public Builder orderedRoute(String route, Integer order) {
            orderedRoute(route, order, null);
            return this;
        }

View on GitHub (pinned to e1c734241f)

Solutions

1. Replace the call with routeFunction(String route, Consumer<Route>) passing an explicit path, e.g. builder.routeFunction("/my-endpoint", route -> route.handler(handler))
2. If a Router-level function is required, use the Builder's orderedRoute(path, order, consumer) methods which accept paths
3. Check which builder class you hold: NonApplicationRootPathBuildItem.Builder disallows the Function overload while other route builders allow it

Example fix

// before
builder.routeFunction(router -> router.route("/framework/foo").handler(handler));
// after
builder.routeFunction("/framework/foo", route -> route.handler(handler));

boolean isNonAppBuilder = builder instanceof NonApplicationRootPathBuildItem.Builder;
if (isNonAppBuilder) {
    // use routeFunction(String, Consumer<Route>) only
    assert path != null && !path.isBlank() : "non-application routes need an explicit path";
}

boolean supportsFunctionOverload(Object builder) {
    return !(builder instanceof NonApplicationRootPathBuildItem.Builder);
}

When it happens

Trigger: Calling builder.routeFunction(Function<Router,Route>) on the Builder obtained from a NonApplicationRootPathBuildItem's Builder constructor; the throw is unconditional on that overload.

Common situations: Extension authors porting code that builds application RouteBuildItems (where the Function overload is legal) to non-application root (framework/dev console/management) routes; copy-pasting a builder chain that used the Function overload elsewhere.

Related errors

• Cannot display <routeFunction> on not found page as no expli
• 'RouteBuildItem$Builder.routeFunction' was not set. Ensure t
• Cannot discover value of <routeConfigKey> as no explicit pat
• Cannot display <routeFunction> on not found page as no expli
• Too many default routes.

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/42a67b0265c822da. Report an issue: GitHub.